Resonator Device Phase Shift for Magnetic Resonance Homogeneity
Solution Overview
Problem
Magnetic resonance systems face challenges in producing a homogeneous microwave or radio-frequency magnetic field across a three-dimensional sample, particularly in reducing vortex losses and maintaining a high quality factor, especially when aligned with the direction of current flow in conductors.
Innovation Solution
A resonator device featuring two parallel half-wavelength transmission line resonators fed differentially by narrowband baluns with delay lines, which produce a 180-degree phase shift, reducing vortex losses and enhancing the magnetic field strength, and utilizing a dielectric substrate with conductors and a ground plane to create a microstrip transmission line structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional resonator structures are used to produce microwave magnetic fields, then the magnetic field can be generated, but vortex losses occur and the quality factor decreases
Solution Approach 1:
The resonator is divided into two parallel half-wavelength transmission line resonators that are fed differentially. This segmentation allows the magnetic field to be generated through differential current flow, which eliminates vortex currents in the conductor and reduces associated energy losses, thereby improving the quality factor
Solution Approach 2:
Instead of using conventional single-ended feeding that produces vortex losses, the invention uses differential feeding where currents flow in opposite directions in the two resonators. This inverted approach causes magnetic fields to add constructively while electric fields cancel, eliminating vortex losses and enhancing the quality factor
2Reliability
If conventional resonator configurations are used, then magnetic field can be produced, but the field is not homogeneous across the three-dimensional sample
Solution Approach 1:
The invention transitions from two-dimensional planar resonator configurations to a three-dimensional differential structure with parallel resonators. This dimensional change enables homogeneous magnetic field distribution across the entire three-dimensional sample volume by creating uniform field patterns in all spatial dimensions
Solution Approach 2:
The resonator structure is designed with specific local characteristics including parallel configuration, differential feeding, and half-wavelength transmission line sections. These localized structural qualities ensure that the magnetic field maintains homogeneity throughout the sample region while managing the overall device complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resonator device achieves a substantially uniform microwave magnetic field across a three-dimensional sample, reducing vortex losses and increasing the magnetic field strength, thereby improving the quality factor and operational efficiency in magnetic resonance applications.
Implementation Method 1
narrowband baluns with delay lines, which produce a 180-degree phase shift
Implementation Method 2
a resonator manipulates the spins by producing a magnetic field at a frequency near the spins' resonance frequencies
Implementation Method 3
two resonators that are parallel to each other and fed differentially by baluns configured to operate at the resonant frequency of the resonators
Implementation Method 4
produce a microwave or radio frequency magnetic field that is substantially homogeneous across the sample in all three spatial dimensions
Implementation Method 5
reducing vortex losses and enhancing the magnetic field strength
Implementation Method 6
fed differentially by baluns configured to operate at the resonant frequency of the resonators
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
In some aspects, a resonator device includes a dielectric substrate, a ground plane on a first side of the substrate, and conductors on a second, opposite side of the substrate. The conductors include first and second resonators and two baluns. Each balun includes a feed, a first branch and a second branch. The feed is connected to the first and second branches, and the first and second branches are capacitively coupled to the respective first and second resonators. The first branch includes a delay line configured to produce a phase shift relative to the second branch. The resonator device includes a sample region configured to support a magnetic resonance sample between the first and second resonators.